THERMAL-DIFFUSIVITY MEASUREMENT OF NEAR-PSEUDOBINARY HGCDTE SOLID AND MELT, TE-RICH HGCDTE AND HGZNTE MELTS, AND PURE TE SOLID AND MELT BY THE LASER FLASH TECHNIQUE

The thermal diffusivities of mercury cadmium telluride, (Hg1-xCdx)1-yTey, and mercury zinc telluride, (Hg1-xZnx)1-yTey, with 0.55 less-than-or-equal-to y less-than-or-equal-to 1.0 and 0.0125 less-than-or-euqal-to 0.054 65, and of pure Te were measured from 350 to 850-degrees-C by the laser flash technique. The diffusivity of near-pseudobinary Hg1-xCdxTe solids decreased more rapidly with temperature approaching the melting point than did pseudobinary solids previously reported: The solid diffusivity for x = 0.028 17 and y = 0.55 was 0.83 mm2/s at 371-degrees-C, decreasing to 0.22 mm2/s at 614-degrees-C. The diffusivity of Te-rich (Hg1-xCdx)1-yTe melt increased with x and with temperature: The melt diffusivity for x = 0.039 36 and y = 0.782 was 0.91 mm2/s at 485-degrees-C, increasing to 4.93 mm2/s at 851-degrees-C. For Te-rich (Hg1-xZnx)1-yTe melt with x = 0.0125 and y = 0.7944 there appeared to be a minimum diffusivity of about 2.6 mm2/s near 690-degrees-C. The thermal diffusivity of pure Te solid was 0.97 mm2/s at 300-degrees-C and decreases to 0.64 mm2/s at 439-degrees-C. The melt diffusivity of pure Te was 1.52 mm2/s at 486-degrees-C, increased to 3.48 mm2/s at 584-degrees-C. Experimental data presented can be used to calculate the thermal conductivity needed for designing systems capable of growing a better quality single crystal of these materials.